29 CFR 1910.1000: Air contaminants
The official text is on the eCFR. Below: how the section is organized, the paragraphs our CSP questions are built on, and free questions to try.
Quoted from the eCFR, current as of 2026-10-14; last amended 2017-05-30.
How 29 CFR 1910.1000 is organized
- (a)2 paragraphs
- (b) Table Z-24 paragraphs
- (c) Table Z-31 paragraph
- (d) Computation formulae32 paragraphs
- (e)694 paragraphs
Paragraphs our practice questions cite most
Counted across the 3 live PassCited questions on this section: our bank, not the real exam.
“(ii) To illustrate the formula prescribed in paragraph (d)(1)(i) of this section, assume that Substance A has an 8-hour time weighted average limit of 100 ppm noted in Table Z-1. Assume that an employee is subject to the following exposure:”
“(2)(i) In case of a mixture of air contaminants an employer shall compute the equivalent exposure as follows:”
“(e) To achieve compliance with paragraphs (a) through (d) of this section, administrative or engineering controls must first be determined and implemented whenever feasible. When such controls are not feasible to achieve full compliance, protective equipment or any other protective measures shall be used to keep the exposure of employees to air contaminants within the limits prescribed in this section. Any equipment and/or technical measures used for this purpose must be approved for each particular use by a competent industrial hygienist or other technically qualified person. Whenever respira…”
Free practice questions on 29 CFR 1910.1000
Question 1
An industrial hygienist is evaluating a worker's exposure to a single contaminant with an 8-hour TWA limit of 100 ppm. The worker spent 2 hours at 150 ppm, 2 hours at 75 ppm, and 4 hours at 50 ppm. Which conclusion is correct?
Show answer and source
Answer: D. The 8-hour TWA is 81.25 ppm, which is below 100 ppm, so the exposure is acceptable
OSHA's air contaminants rule, 29 CFR 1910.1000(d)(1)(ii), weights each concentration by its duration: (2 × 150 + 2 × 75 + 4 × 50) ÷ 8 = 81.25 ppm. That is below the 100 ppm limit, so the exposure is acceptable. A brief period above 100 ppm does not by itself fail an 8-hour time-weighted average (TWA). The 91.7 ppm and 100 ppm figures are miscalculations.
Answer D rests on
29 CFR 1910.1000(d)(1)(ii)(opens ecfr.gov in a new tab)“Substituting this information in the formula, we have (2 × 150 + 2 × 75 + 4 × 50) ÷ 8 = 81.25 ppm Since 81.25 ppm is less than 100 ppm, the 8-hour time weighted average limit, the exposure is acceptable.”
Where it shows up in exam prep
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Other Part 1910 sections
- 29 CFR 1910.1020: Access to employee exposure and medical records
- 29 CFR 1910.1030: Bloodborne pathogens
- 29 CFR 1910.1053: Respirable crystalline silica
- 29 CFR 1910.106: Flammable liquids
- 29 CFR 1910.119: Process safety management of highly hazardous chemicals
- 29 CFR 1910.120: Hazardous waste operations and emergency response
A study aid, not legal advice or an official interpretation. Always check the current eCFR text.